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P0452 EVAP PRESSURE SIGNAL LOW CODE ON 2000 GMC 5.3 GAS
I WAS WORKING ON A 2000 GMC 1500 5.3 WITH A P0452 CODE FOR A PRESSURE SENSOR FAILURE. WHEN I UNPLUGGED THE SENSOR AND CHECKED 5V REFERENCE AND SIGNAL WIRE I GOT 5V ON BOTH. MY QUESTION IS THIS. WITH THE SENSOR PLUGGED IN VOLTAGE ON THE PRESSURE SENSOR SHOW 0 VOLTS. WHEN I UNPLUG THE SENSOR HARNESS FROM THE SENSOR THE SCANNER DATA WENT TO 2+ VOLTS. mY QUESTION IS, THE 2 + VOLTS IT SHOWED AFTER UNPLUGGING THE SENSOR, WAS THAT HALF OF THE 5V REFERENCE ON THE 5 V CIRCUIT? IT THAT A NORMAL CHANGE ON THE SCAN DATA. IF SO THEN JUST UNPLUGGING THE SENSOR WOULD TELL ME THAT THE SENSOR NEEDS TO BE REPLACED. NOT THAT IT WAS TOO HARD TO CHECK VOLTAGE READINGS, JUST CURIOUS WHERE THE 2+ VOLTS CAME FROM
It’s a pull down sensor. The pcm sends 5 volts on the signal wire. Just like a cam sensor some are pull up some are pull down. Just have to check the voltage on the signal wire to 3 wire sensors unplugged
Thanks Cheryl. Just never seen it before. Probably because I’ve never looked at the scan data when unplugged the sensor! Or can’t remember looking at it.
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